Is the foam going to off gas formaldehyde into my house? No, formaldehyde foam was a system on the market years ago and was a completely different product than urethane foam. Urethane foams do not off gas anything harmful to you. The refrigerator that you keep your food in is insulated with urethane.
Can the foam be left exposed? All model-building codes require an approved 15-minute thermal barrier on the habitable side of a structure between the interior and the foam. Because spray foam, like most other organic materials, is combustible, when it is exposed to fire sources it may ignite. The burning will be brief, forming a layer of less flammable surface char. This initial burning produces combustible gases and black smoke. In confined interiors these combustible gases can ignite resulting in flash over. This code requirement also applies to foam board stock such as Styrofoam. In most cases 1/2 sheet rock meets the code requirements although we can also spray apply thermal barriers.
If I use foam in my walls and I want to run an electrical wire, can I do it? In any wall that is insulated correctly it would be difficult to run a wire later, however a good electrician should still be able to do it, or in most cases the wire could run through the interior partitions where there is no insulation.
Isn’t this foam stuff a fire hazard? All foam plastics used in the construction industry must have a Class 1 fire rating. To gain Class 1, the product must meet ASTM – E – 84 which has a flame spread of 25 and smoke developed “Less than 450”. The wood in your home is not Class 1.